The drug Tamiflu recently made headlines when independent researchers revealed it wasn’t effective at actually fighting the flu. Roche, Tamiflu’s maker, had known this but withheld clinical data saying so. While this was unwelcome news for flu sufferers, the resulting scandal demonstrated just how little we actually know about the medicines we take.

In April the European Parliament voted for the new Clinical Trials Regulation, which significantly increases the amount of data that pharmaceutical companies must release about drug effectiveness. And it has changed the E.U. legal framework so that—for the first time—companies cannot use “commercial confidentiality” as a blanket excuse to withhold their data.

the European Medicines Agency set up and run a new, public clinical trials register;

a summary of the clinical trial results that is “understandable to a lay person” is published on the register within a year; and that

comprehensive, detailed, and structured documents on trial results, called Clinical Study Reports, are be made publicly available.

This new EU transparency policy goes well beyond the U.S. Food and Drug Administration's, which only requires a summary of the trial to be publicly available. The new EU policy requires that drug data “should not be considered commercially confidential once a marketing authorisation has been granted, the decision making process on the application for a marketing authorisation has been completed, or an application for marketing authorisation has been withdrawn.”

But this victory for transparency is only partial.

It only applies to new drug authorizations starting in 2016. There is also no obligation to publish all individual patient trial data. And it has much lower reporting requirements for trials undertaken on drugs that have already been approved for the market. These post-approval trials are intended to demonstrate real-world efficacy, but often just provide marketing collateral for drug companies. The policy also fails to mandate that companies compare the new medicine against the existing “gold standard” treatment, as opposed to the common practice of comparison with a placebo. This helps determine whether a new drug actually has a therapeutic advantage over existing treatments.

The clinical trials regulation has been an important step forward—and light has begun shining on the shadowy world of drug data. But the movement for transparency must remain organized and vigilant if we are to advance an evidence-based public health agenda—one that doesn’t respond to the needs of flu sufferers based on little more than Roche’s say-so.